This invention relates to magnetic tape systems for use in door answering devices, and more particularly, to magnetic tape systems of the type having noise activated triggering circuitry for transmitting a prerecorded message to a person generating noise from outside the door of a structure.
In the field of electrical communications design, voice and noise activated relays are well known particularly in radio transmission. Noise activated relays were used by amateur as well as professional radio operators for eliminating the requirement of depressing the press-to-talk switch each time the operator spoke into the, communications microphone. In this application, the operator's voice would be transmitted over the airways as long as the operator continued to talk. However, after a few seconds of silence, the transmission, would cease until the relay was reactivated by the operator's voice.
Other examples of the use of voice/noise activated relays included operating tape magnetic systems of the past and computer activated systems employed for operating smoke/fire detection systems. Such a detection system sensed the elements of combustion, announced via synthetic voice circuitry the presence of the elements of combustion, completed a communications telephone circuit to an area fire department, and activated a local fire control system. The activated fire control system thereafter energized an electrical solenoid for releasing water or chemical retardant from a fire main.
Current uses of voice/noise activated relays and switches occur in magnetic tape recorders for preventing silent gaps on the tape caused by pauses in the audible noise level. Under these conditions, recording only occurs in the presence of audible sound. This application occurs in the use of voice-activated tape recorders and has the advantages of economizing on time and magnetic tape. However, when voice/noise activated recorders are employed, mechanically actuated linkage is utilized to initially set the machine in the "record" mode. Under these conditions, the linkage positions the magnetic head and the capstan rollers in contact with the magnetic tape. Thereafter, the presence or absence of voice actuation determines if a drive motor will move the magnetic tape to record material or stop the motor and permit the tape to stand. This stop and go action of the magnetic tape is acceptable for temporary periods for eliminating the silent gaps on the tape. However, prolonged stationary contact of the magnetic head and the capstan roller is undesirable due to the magnetic construction of the head and the tape. In addition, the circular construction of the rubber capstan can become distorted after being in this stationary position for an extended period of time. Thus, a means for releasing the head and capstan from the tape during periods of non-operation is necessary for protecting the system components from excessive wear.
Other uses of voice/noise activated devices included switching electrical appliances such as lamps. Such a device was placed in a dark hallway and was activated by the voices of or the noise created by persons entering the hallway area. The lamp would then be energized by the switching action for providing illumination in the hallway. After the area was vacated, the absence of voice/noise would subsequently result in deenergizing the lamp. Further applications of voice/noise activated systems included devices which sensed a voice with a receiver-microphone circuit and thereafter actuated controls for recording the voice.
As can be seen, voice-activated relays and switches can and have been employed in a wide variety of applications. However, such voice/noise activated relays have not normally been utilized in burglar sensing devices because of false triggering circuit characteristics. It would be undesirable to have a siren or bell sound each time a voice/noise was intercepted by a microphone receiving circuit associated with the device. Therefore, infrared detectors, motion detectors, glass breakage detectors and other switching devices were common choices in alarm system design for detecting unauthorized entry and intrusion.
In certain complex computerized alarm systems, voice synthesized announcements have been employed for indicating when a particular monitored zone was violated. These systems were usually limited to industrial applications which included complex sensing devices and wiring schemes. Only in an industrial application could such an elaborate and costly system prove cost effective. However, completely computerized home management systems have been available on the market and perform a plurality of tasks automatically. Such systems can control electrical and electronic devices in an energy efficient manner and act to protect the structure against intruders. The devices, which are generally very expensive, rely on infrared sensors and an intrusion detection system that will operate lights, bells, or other alarm devices. Once an intruder is detected, an alarm activates and will deactivate only upon the recognition of a voice previously stored in the computer memory.
In light of the foregoing, there does not exist a voice/noise activated device which incorporates a magnetic recording system for playing a prerecorded message to an intruder upon the sensing of a voice or noise prior to entry by the intruder into the structure. Only after entry into the structure do the alarm systems of the past detect the intruder and thereafter sound an alarm or project a recorded message. Once the intruder has entered the structure, it takes but a short time to commit a larceny and escape. In order to create an image that the resident was at home, appliances such as the electric lights, radios and televisions were left operating. Such an image discouraged the unauthorized intrusion by burglars.
Hence, those concerned with the development and use of voice/noise activated intrusion devices in the electrical communications field have long recognized the need for improved intrusion devices which create the image that the resident is at home for deterring burglaries prior to the occurrence of a break-in, announces a plurality of prerecorded messages in a timed fashion after a voice or noise has been detected, exhibits a high level of sensitivity which permits capturing the sound of a door knock or a door bell when initiated from a distant location, employs hardware including electronic solenoids for minimizing wear on system components, is self-contained and portable requiring no additional sensing devices for operation, and is an economical burglary deterrent compared to other systems of the past. The present invention fulfills all of these needs.